As a result of increased operating costs as well as increased maintenance costs it is a common goal of process system users, manufacturers and facility owners to monitor various components, sub-systems and the like. This monitoring can accomplish a wide variety of goals, one of the most important being energy management. This is particularly so since energy costs comprise a substantial portion of the overall cost for operating a process system having even a moderate amount of complexity.
Such type of process systems can be varied but may include processes and manufacturing lines, assembly lines, as well as Heating Ventilation and Air-conditioning Control (HVAC) Systems. Such HVAC systems may be found in buildings ranging from small facilities with less than 10,000 ft..sup.2, including malls up to large multi-story buildings and large shopping malls incorporating at least hundreds of thousands of square feet.
Heretofore, attempts to reduce and coordinate energy control, although taking many forms, have essentially been time of use or occupancy sensor based. That is, devices which merely shut off equipment during a particular time of the day or do so by sensing that there is no user physically present. These types of occupancy or use sensors are becoming quite common to turn off lights or turn off heating and air-conditioning control systems. The most advanced improvements have merely used sensors such as outside temperature sensors which help decide how far in advance the system must be energized so that the system may operate at the desired comfort level at a predetermined time.
However, all of these systems essentially turn on or off the entire system or portion of the system without regard to or coordination between related components, subsystems and the like. Even when there has been an attempt to modulate system output, this modulation has consisted of merely speeding up or slowing down a single part of the system. One such example may be found in Canadian Patent Number 1,246,714. There, apparatus is used to control the speed of a brine pump motor with respect to refrigeration equipment utilized in an ice rink. That system uses sensors which are utilized to detect variations in the ice slab thermal load. The brine pump or refrigeration equipment motor is then varied in speed in response to such measurements. However, even there, there is no coordination between the brine pump and the refrigerator compressor. Hence, the individual components making up the system are not operatively interconnected.
However, the improvement of varying the speed is significant and has been tried in some circumstances. This approach of using an adjustable speed drive is now manufactured by a number of companies including the same assignee as the present invention. These adjustable speed drives are effectively solid state motor controllers which operate motors in the fractional horsepower range up through thousands of horsepower. These types of drives are retrofitable to existing motors and apparatus or may be provided as part of new installations. However, these drives are typically expensive and hence unless they are fully utilized, their cost can be hard to justify.
With the implementation of these electronic adjustable speed drives, true infinite variable speeds may be achieved as opposed to "step" functions by previously known devices. However, although these types of drives can and often are operated in conjunction with computers, they have heretofore only dealt with specific portions of a system. Therefore, they are in effect stand alone.
Adjustable speed drives have been made and adapted to operate with centrifugal fans, pumps, compressors, chillers and the like. However, even though efficiency is improved, these various sub-components do not communicate with each other.
It is therefore desirable and an object of the present invention to produce a method and apparatus which coordinates the operation of various equipment in a process system. It is also desirable and another object of the present invention to produce a method and system such as a flexible process controller which may control the HVAC system in a facility.
It is also desirable and another object of the present invention to produce a flexible process controller which coordinates the operation, through-put and use of a cooling tower, condenser pump, chiller, and chilled water pump in response to building load. It is still yet a further object of the present invention to produce a flexible process controller which anticipates building or process loads and controls or anticipates the control of same in a timely fashion with optimum energy savings and/or power factor control thereby minimizing operating costs.
Still a further object of the present invention is to produce a method and apparatus for minimizing maintenance and wear and tear or controlling same in a cost efficient or timely manner. Yet another object of the present invention is to monitor and sample various operating parameters, conditions and the like of various components in a process system.
Yet another object of the present invention is to produce a method and apparatus which may be computer controlled at a local or remote station. Still yet another object of the present invention is to produce a method and apparatus which operates with and may be coordinated with variable speed drives.
Still a further object of the present invention is to produce a method and apparatus which may be retrofitted to existing equipment or utilized with respect to new installations of process systems including HVAC systems. Yet another object of the present invention is to produce a method and apparatus which takes into account the operating characteristics and design parameter of specific components utilized therein. Still another object of the present invention is to produce a system and apparatus which may be easily controlled by an operator. Yet another object of the present invention is to produce a method and apparatus which may be easily modified by a user/operator. Still a further object of the present invention is to produce a method and apparatus having an operator interface which may be used or controlled via various displays such as a color graphics display, key pad with an alphanumeric screen or without a dedicated operator.
It is still a further object of the present invention to produce a method and apparatus which may be run in a windows type software environment utilizing a standard graphics user interface commonly known or available. Still a further object of the present invention is to produce a method and apparatus wherein the operator interface allows operation within certain limits or controls various sub-components and adjacent components in response to changes instituted by the operator or one component or sub-system. Still a further object of the present invention is to produce a method and apparatus which can take full control of all the equipment of the entire process or may monitor just a portion thereof and which may provide notice to the operator of various maintenance considerations such as warnings, schedules and the like.
It is yet another object of the present invention to produce a method of flexible process control or operation comprising the steps of: (a) receiving data from instrumentation which monitors a plurality of parameters and overall operation of the plurality of operatively connected process control equipment; (b) interpolating the data from the instrumentation as a function of predetermined control and limit parameters; and (c) controlling the operation of at least one portion of the process control equipment and the overall operation and the interoperation of the operatively interconnected process control equipment in response to overall control criteria.
Still another object of the present invention is a device for flexible process control of a plurality of operatively interconnected process control equipment, comprising: instrumentation operatively connected to the process control equipment for monitoring a plurality of process control parameters and producing data representative thereof; a control devive operatively connected to the process control equipment for implementing process changes to the process control equipment; and a flexible process controller connected to the instrumentation and to the control device for coordinating the operation of at least one portion of the process control equipment, the overall operation and the interoperation of the plurality of operatively interconnected process control equipment in response to overall control criteria and as a function of data from the instrumentation.